A GUNMAN shot dead his teacher mother at their home, and then drove to her school and murdered 20 young children in her classroom in America's worst school shooting.

At least 27 people died when the masked man, named by police as Adam Lanza (20), fired more than 100 shots at Sandy Hook Elementary School in the sleepy town of Newtown

The gunman, dressed in black body armour, was among the dead

Terrified students were told to close their eyes as police rescuers rushed them from the scene past the bodies of classmates – some as young as five

"Our hearts are broken today," US President Barack Obama said, wiping tears from his eyes during an emotional address after the atrocity

He said the nation had been "through this too many times" and has to come together to take meaningful action, "regardless of the politics"

The school teaches children between the ages of five and 10. The victims were reported to be among the youngest in the school. Children told how they fled for their lives through nearby woodland and back yards while other survivors, some crying, were led away in a line with their hands on the shoulders of the child in front of them

As the 600 pupils of Sandy Hook filed into morning lessons on a bright, chilly morning in Newtown yesterday, Dawn Hochsprung, the school's headmistress, sat down for a meeting in her office with six colleagues.

"You really couldn't ask for a better principal," said Lisa Procaccini, the mother of an eight-year-old pupil at the school. "A beautiful person, so warm and personable."

Suddenly, at about 9.30, they heard a loud "pop-pop-pop" from the hall. Mrs Hochsprung, 47, rushed outside with one of her deputies and the school psychologist. Only one came back.

Bloodied by a gunshot wound in the leg, the vice-principal crawled back inside the office, frantically urging colleagues to call 911. The recurring nightmare for parents and teachers across the US was real.

Huddled

Dressed in black, armed with multiple weapons and apparently wearing a bulletproof vest, the gunman, named locally as Adam Lanza, 20, had begun opening fire in a "concentrated area" of the school, believed to be a kindergarten classroom.

Police in Newtown, a picturesque and prosperous town an hour's drive from New York, were sent to the scene and quickly joined by state troopers and authorities from surrounding towns.

"I was in the gym," one pupil told reporters outside later. "We heard lots of bangs and we just thought it was the custodian knocking things down. But then we heard screaming.

"And so," he said, his voice cracking with emotion, "we moved to the wall, and sat down and we cried. Police ran in and said, 'Is he in here?' Teachers said to get to a safe place, so we went into the closet."

Frantically checking what Lt Paul Vance called "every door, every crack and every crevice" for potential victims, police and teachers huddled children into the backs of classrooms around the school as they scoured the scene for the shooter.

In one classroom, Alexis Wasik and her friends were terrified. "There were all these people," she said. "We saw police officers, and heard them on the roof and on the building."

Parents were soon receiving an automated "code red" phone message from the local school superintendent, alerting them to a shooting at the school. They rushed to the scene.

One, Stephen Delguidice, told reporters how a forward-thinking teacher may have saved lives by hitting the button on the school public address system, alerting pupils and teachers to the intruder.

"My daughter said she heard cursing come over the loudspeaker and that cursing wasn't the right thing; so the teacher, Mrs Martin, looked at the kids and she said, 'Get in corner'," said Mr Delguidice.

"She did a very good job. She locked the door and that basically saved their lives, I think."

Mr Delguidice said he had rushed to the school after receiving an alert on his mobile phone.

"I just wanted to see her face," he said, recalling his desperation to see his eight-year-old daughter. People were running for their kids. It was just mass chaos. I finally got to my daughter."

Tears streaming down their faces, dozens of other parents gathered outside were clutching their children.

By 10.30am, President Barack Obama was being briefed on the crisis by John Brennan, his homeland security adviser. All Newtown schools were locked down to ensure the safety of students and staff.

Inside Sandy Hook, however, it was too late. Lanza, who is thought to have come from the area but moved to Hoboken, New Jersey, appeared to have quickly killed about 27 people, 20 of them children. He was killed inside the school.

Police, who said Lanza was "not a stranger" to the school, declined to say how he had died. There were unconfirmed reports last night that one of his parents had been found dead at a property in New Jersey.

Officers were also believed to be questioning another man in connection with the shooting. Witnesses said they saw a handcuffed man, dressed in camouflage, led out of a nearby wood.

Anxious

Few gathered at the scene last night could believe that this was happening to them.

"This is a nice town, this is a good school, things like this don't happen here," one witness told reporters.

Mrs Procaccini said she did not know how she would explain to her child what had happened. Other mothers and fathers, meanwhile, continued to endure an anxious wait, fearing that a far worse task awaited them.